Performance Analysis of MPPT Algorithms for PV Array Fed ...idosi.org/ejas/9(3)17/4.pdf · These algorithms are applied to a Single Ended Primary Inductor Converter (SEPIC) using

European Journal of Applied Sciences 9 (3): 124-132, 2017ISSN 2079-2077© IDOSI Publications, 2017DOI: 10.5829/idosi.ejas.2017.124.132

Corresponding Author: K. Nandhakumar, Department of EEE, PSNA College of Engg and Tech., Dindigul-624 622, Tamil Nadu, India.

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Performance Analysis of MPPT Algorithms for PV Array Fed Sepic Converter

K. Nandhakumar and P. Alageswari

Department of EEE, PSNA College of Engg and Tech., Dindigul-624 622, Tamil Nadu, India

Abstract: This work deals with the application of Maximum Power Point Tracking (MPPT) Algorithm like Perturband Observe and the Incremental Conductance algorithms for photovoltaic (PV) applications usingMATLAB/SIMULINK. These algorithms are applied to a Single Ended Primary Inductor Converter (SEPIC)using a mathematical model. The proposed methodology algorithm can be expanded to a various class ofconverters which is capable for photovoltaic applications. The SEPIC converter provides the close loopcharacteristics. The mentioned algorithms i.e. Perturb and Observe and Incremental Conductance algorithmsare compared in terms of their fastness and error for the proposed Single Ended Primary Inductor Converter.

Key words: Photovoltaic (PV) Maximum power point tracking (MPPT) SEPIC converter Perturb andObserve (P&O) Incremental Conductance (INC).

INTRODUCTION panel [5, 6]. The controller is used to trace the peak power

Now a day, Renewable energy resource are becoming thereby improving efficiency of the overall systems. popular as they provide major part energy to energy of This paper proposes a control scheme, how hillless consuming building [1]. Between the all renewable climbing and incremental conductance algorithms areenergy resource, solar power systems plays a vital role used to track peak power obtained from solar panel thatsince they gives better opening to generate power and can be used to operate the load using SEPIC converter.continues to grow in popularity [2, 3].

Photovoltaic (PV) array has variety of applications Proposed Methodology: The proposed system blocksuch as the power house appliances, solar car and diagram is shown in Fig. 1. This strategy of poweraircrafts. The solar panel output power changes in production contains of PV panel, SEPIC converter,fraction of seconds due to rapid climatic changes like perturb and observe/incremental conductance controller.weather condition rises or reduce in ambient temperature The PV array converts the sun light into electrical power.[4]. The generated power is fed to the SEPIC converter and

In the lower efficiency of solar module, various the activating pulse to the converter is given by perturbtechniques are introduced, the recent idea known as and observe algorithm or incremental conductance“maximum power point tracking” (MPPT). The MPPT algorithm. The MPPT algorithm will continue untilalgorithms are used to improve the output power of the maximum power obtained from PV panel. Hence the loadPV panel. In the development of solar panels, maximum is sustained to operate at peak power.power point tracking algorithm is the electronic method ofelectrical load to attain the highest obtainable power, Photovoltaic Model: Photovoltaic array is designed induring second to second changes in sun light, shadow, series/shunt combination of solar cells [7], the circuitheat from the sun and solar PV system features. The representation is shown in Fig. 2.single ended primary inductor converter (SEPICconverter) is used. The converter is used to avoid the The current cell equation is given by, fluctuation that is obtained by the solar panel output.This converter is connected between the load and the PV I = I - I (1)

of PV panel and control action is taken in the PV systems

L D

exp 1/

sD o

V IRI InkT q

+= −

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Fig. 1: Block diagram of the proposed methodology

Fig. 2: Simplified circuit of PV panel

The current diverted through diode is given by, which is most efficient and popularly used. It can be work

(2) boundary condition mode. The duty cycle of the SEPIC

The current source that delivers short circuit current. improves the tracking efficiency of the solar PV array.The resistance is connected in series and parallel with the SEPIC’s are useful in battery voltage that can vary thecurrent source. The diode is connected parallel with the regulator’s calculated output. A SEPIC converter consistssource that provides the p-n junction. That will provide of a coupling capacitor, C and output capacitor, Ceither voltage or current. The current I is produced which coupled inductors L and L and diode as shown in Fig. 3.d

is called diode current or dark current. Fig. 4 shows the converter when switch is on. The

where the symbol are given as follows, L at this time. The energy is drawn from the inductor L

I – Reverse saturation current, A obtained by the load current. The load capacitor does noto

n – Diode ideality factor supply energy at that time. The polarity of the InductorT – Absolute temperature current and capacitor voltage are also decided.e – Electron charge (1.602*10-19 C) Fig. 5 shows the converter when the switch is off, theq – Elementary charge current given to load system is obtained by charging thek – Boltzmann constant (1.38*10-23 J/K) capacitor C by inductor L . The load will be connected toI – Diode current, A the inductor L at that time. This operation is done whenD

I – Photo generated current, A the output capacitor will capture a current pulse, basicallyL

R – Series resistance of cell noisier than a buck converter. The SEPIC converter iss

Proposed Converter: While choosing an MPPT algorithm, array.the important thing is to select and design a very goodconverter, which is operated as the major part of MPPT. The duty cycle is formulae by, The switching mode supply DC-DC converter efficiencyis mostly used. The high efficiency is obtained by using (3)switching mode power supply [8].

Among the entire converters available, single ended (4)primary inductor converter (SEPIC) is a DC-DC converter

in all modes such as continuous, discontinuous, or

converter is controlled by the control transistor [9-12].SEPIC converter has low ripple and no pulsating. It

1 2,

1 2

input voltage source is obtained by charging the inductor1 2

through the capacitor C and the output capacitor is1

l 1

2

most efficient and it will track maximum efficiency in solar

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Fig. 3: SEPIC converter circuit diagram

Fig. 4: SEPIC converter when switched ON

Fig. 5 SEPIC converter when switched OFF

Proposed Algorithm: There are wide number of Perturb and Observe MPPT: The P&O algorithm is alsoalgorithms used to trace maximum power. Some of the called as hill climbing method. This method is most widelyalgorithms are simple and easy, such as current and used. The implementation of this method is easy and costvoltage method and some are more difficult, like hill is less. This method will do track sudden changes and itclimbing (P&O) and incremental conductance (INC) will not reach maximum power. At the maximum power itmethod. These algorithm changes in steady state, sensor rises or reduced repeatedly depends upon the referenceessential, occurrence of speed , price, range of voltage and current. performance, acceptance, to perform more versatile and its During dP/dV>0 the MPPT algorithm will traceuses [10, 11]. maximum power available in solar cell. This method will

P&O algorithm is the easier method. In this only one continue to track in the same direction. During dP/dV<0 itsensor is used, i.e. voltage sensor, to sense the solar will track above the maximum power obtained in solar cell.panel voltage and the price of operation is lower. So it is This topology will reverse the direction of search. Thiseasily implemented. topology results in unstable output power. The algorithm

INC conductance method is the one which is widely is obtained in MATLAB/Simulink. used in all type of weather conditions. In this topology,the output voltage of the solar cell is varied depend upon Incremental Conductance MPPT: The output power fromthe peak power voltage. According to the incremental the solar PV is obtained by the incremental conductanceand instantaneous conductance the PV system is method in reference to the voltage and the peak power willestablished. be equivalent to zero.

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Fig. 6: Flowchart of P&O MPPT method

Fig. 7: Flowchart of INC MPPT method

( ) 1 0dP dIV dIVdV DV dV

= = + =

1 dIV dV− =

I IV V∆ = −∆

I IV V∆ > −∆

I IV V< −

∆

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(5) Fig. 10 shows two waveforms i.e. MPPT output and

(6) increase. If the irradiation increase means, the output

The Eqn. (5) denotes the instantaneous andincremental conductance of PV array. In peak power, the At constant temperature (T=70°) with the changes inparameters should be same in magnitude, but different irradiation (S=800 to 600w/m )polarities. The eqn. (6) that indicates the peak powervoltage will be higher or lower the operating voltage. This Fig. 12 shows two waveforms i.e. MPPT outputrelation is shown in eqns. (7, 8, 9). and output power. If the temperature is increased

at the MPP (7) power starts to reduced when compared to Fig. 10.

Left of the MPP (8)

Right of the MPP (9) first step is to read the PV array voltage and current.

The present and earlier value is calculated using voltage and current in maximum peak power (MPP).dI and dV of the PV voltage and current. This By summing the present value and previous value, ifincremental conductance method has an advantage it is greater than zero means duty ratio is reduced, ifthat it can achieve the peak power and it also find out it is less than zero means duty ratio is increased, if itwhen it reaches the peak power. This method does not is equal to zero means voltage and current will beoscillate around the peak power point. stored. This process is done until it gets maximum power

Simulation Result: The proposed system consists ofthe PV circuit model, SEPIC converter, MPPT algorithm At constant temperature (T=25°) with the changes inand it is designed using MATLAB as shown in Fig. 8. the irradiation (S=800 to 600w/m )The PV panel output power is determined by the electricalcircuit model of solar array. The PV array that provides Fig. 15 shows two waveforms i.e. MPPT output andvoltage and current is given to the converter and output power. If the temperature is reduced means, powercontroller simultaneously. The SEPIC converter will adjust will starts to increase. Here T=25° so power starts tothe duty cycle directly. increase. If the irradiation increase means, the output

Simulation Result for P&O Method: The simulink for steady.P&O algorithm is shown in Fig. 9. The PV panel voltageand current is given to MPPT, that will track maximum At constant temperature (T=70°) with changes in thepeak power and the pulse is given to SEPIC converter. irradiation (S=800 to 600w/m )

The algorithm is verified by using the temperatureand irradiance. The MPPT output and output power Fig. 17 shows two waveforms i.e. MPPT outputwaveforms will be obtained according to its temperature and output power. If the temperature is increasedand irradiance. The waveforms are shown below. means, power will start to increase. Here T=70° so

At constant temperature (T=25°) with the changes in If the irradiation increase means, the output power willirradiation (S=800 to 600w/m ) increase.2

output power. If the temperature is reduced means, powerwill start to increase. Here T=25° so power starts to

power will increase. In P&O, the output power will not besteady.

2

means, power will starts to reduce. Here T=70° so

If the irradiation increase means, the output power willincrease.

Simulation Result for Inc Method: The simulink forINC conductance algorithm is shown in Fig. 10. The

The next step is to calculate present and previous

output.

2

power will increase. In INC, the output power will be

2

power starts too reduced when compared with Fig. 15.

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Fig. 8: Simulink diagram for proposed system

Fig. 9: Simulink of P&O algorithm

Fig. 10: MPPT output and output power waveform (T=25° and S=800 to 600w/m )2

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Fig. 11: Output voltage waveform (T=25° and S=800 to 600w/m )2

Fig. 12: MPPT output and output power waveform (T=70° and S=800 to 600w/m )2

Fig. 13: Output voltage waveform (T=70° and S=800 to 600w/m )2

Fig. 14: Simulink of the INC algorithm

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Fig. 15: MPPT output and output power waveform (T=25° and S=800 to 600w/m )2

Fig. 16: Output voltage waveform (T=25° and S=800 to 600w/m )2

Fig. 17: MPPT output and output power waveform (T=70° and S=800 to 600w/m )2

Fig. 18: Output voltage waveform (T=70° and S=800 to 600w/m )2

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CONCLUSION 6. Ravivarman, S. and T. Samydurai, 2015. Optimized

This project presented the application of various Tracking using cascaded SEPIC converter and threeMaximum Power Point Tracking (MPPT) like Perturb & phase inverter, International Journal, 4(1). Observe and Incremental Conductance Algorithms for 7. Villalva, M.G., J.R. Gazoli and E. Ruppert, 2009.photovoltaic (PV) applications using MATLAB/ Modelling and Circuit based simulation ofSIMLINK. These algorithms are applied to a Single Ended photovoltaic arrays, Brazilian Journal of PowerPrimary Inductor Converter (SEPIC) using a mathematical Electronics, 14(1): 35-45.model. The above algorithms i.e. Perturb & Observe and 8. Velmurukan, D., Arun P. Babu and Sandeep Prasanth,Incremental Conductance Algorithms are compared in 2015. A Fuzzy algorithm based MPPT control forterms of their fastness and error for the proposed Single SEPIC converter with Sliding Mode Controller,Ended Primary Inductor Converter. International Journal, 2(1).

REFERENCES Ibanez, 2012. Analysis of inverter voltage influence

1. Sera Dezso, L. Mathe and T. Kerekes, 2013. On the Trans. Ind. Electron., 59(10): 3900-3907.Perturb and Observe and Incremental Conductance 10. Hussein, K., I. Muta, T. Hoshino and M. Osakada,MPPT methods for PV systems, IEEE Journal of 2005. Maximum photovoltaic power tracking: anPhotovoltaics, 3(3). algorithm for rapidly changing atmospheric

2. Femia, Nicola and Giovanni Petrone, 2005. conditions, IEEE Proceeding of Generation,Optimization of Perturb and Observe maximum power Transmission and Distribution, 142(1): 953-959.point tracking method, IEEE Trans. Power Electron., 11. Hua, C.C. and C.M. Shen, 1998. Study of maximum20(4): 963-973. power point tracking techniques and control of

3. Abdel-Rahim Omar, Hamdy Radwan and Mahrous DC-DC converter for photovoltaic power system,Hmed, 2010. Two Stages Maximum Power Point Proceeding of IEEE Power Electronics SpecialistsTracking Algorithm for PV systems Operating under Conference, 1: 86-93.Partially Shaded Conditions, IEEE Trans. Power 12. Mattavelli, P., L. Rossetto, G. Spiazzi and P. Tenti,Electron., 0025, 5. 1993. General purpose Sliding Mode Controller for

4. Patel Jay, Vishal Sheth and Gaursng Sharma, 2013. DC-DC converter applications, Processing IEEE PESCDesign & Simulation of Photovoltaic system using REc, 609-615.Incremental MPPT Algorithm, International Journalof Advanced Research in Electrical, EIE, 2(5).

5. Lokin Joshi and Kaumil Shah, 2013. IncrementalConductance based Maximum Power Point Trackingfor PV Multi-String Power Conditioning Systems,International Journal, 3(4).

grid power injection with Maximum Power Point

9. Alonso, R., E. Roman, A. Sanz, V. Santos and P.

on distributed MPPT architecture performance, IEEE